Comment # 14 on bug 1120405 from Tobias Havla

Ok, I've tested your udev rules and they fix this problem with Xorg. Digitizer
and touchscreen are working fine after creating the 70-wacom-uaccess.rules
file. Thanks for that!
Just to confirm that I am no longer member of the dialout group:
tobias@tbh-NB-ThinkPadX201Tablet:~> groups 
users vboxusers wheel

The behaviour with Wayland didn't change though. Digitizer and touchscreen are
still not working there.